Chairs having arms adjustable in respect of height are very popular because the sitter can rest their arms comfortably on the chair arms having been adjusted to a desired height.
Many adjustment devices for an arm of a chair have be devised, e.g. the ones disclosed in U.S. Pat. Nos. 5,853,223, 5,795,026, 4,828,323 and 4,239,282.
The inventor of the present invention has devised an adjustment device for an arm of a chair, which has a design different from those of the above said devices, and can be used easily.